<template>
  <div class="app">
    父组件 --- 子组件中选中的城市是: {{ cityId }}
    <BaseSelect :cityId="cityId" @changeCityId="cityId = $event"></BaseSelect>
  </div>
</template>

<script>
import BaseSelect from "./components/BaseSelect.vue";
export default {
  data() {
    return {
      cityId: "102",
    };
  },
  components: {
    BaseSelect,
  },
};
</script>

<style>
.app {
  border: 3px solid red;
  width: 400px;
  height: 200px;
}
</style>